Satellite altimetry from the GEOSAT and the ERS-1 geodetic missions provide altimeter data with a very dense coverage. Hence, the heights of the sea surface may be recovered very detailed. Satellite altimetry from the 35 days repeat cycle mission of the ERS satellites and, especially, from the 10 days repeat cycle TOPEX/POSEIDON satellite mission provide repeated height observations, so that the mean sea surface heights along the ground tracks can be recovered very accurately. In this study a global high resolution mean sea surface (1/8 by 1/8 degrees) is constructed using satellite altimetry from those four missions. The mean sea surface fits the TOPEX/POSEIDON mean sea surface heights within 5 cm and the slopes fit within 2.5 mm per km.